1. Field of the Invention
The present invention relates to a coating liquid composition for a photosensitive member for electrophotography, a method of manufacturing a photosensitive member for electrophotography using the coating liquid composition, and a coating liquid composition for a charge transport layer of a photosensitive member for electrophotography.
More specifically, the invention relates to a coating liquid composition containing an aliphatic unsaturated hydrocarbon, having a significantly improved storage stability.
2. Description of the Relates Art
These days, electrophotography technology is widely used not only in copiers but also in various kinds of printers and facsimiles owing to its immediacy and high image quality. The Carlson method, which is a typical electrophotographic technology, comprises a step of charging the surface of an electrophotography photosensitive member (hereinafter also referred to simply as "a photosensitive member"), a step of forming an electrostatic latent image by exposure, a step of developing the electrostatic latent image with a toner and a step of transferring and fixing the visual image on a paper. As the photosensitive member, inorganic photoconductors, such as selenium, cadmium sulfide, arsenic-selenium alloy, zinc oxide and amorphous silicon have been used conventionally. However, recently many photosensitive members utilizing organic photoconductors, which are not hazardous, and can allow easy film formation and manufacture with a better sensitivity to a light beam in a wide range from 400 to 800 nm compared with inorganic photoconductors, are developed and used.
Among the photosensitive members utilizing the organic photoconductor, a laminated function-separated type photosensitive member where a photosensitive layer is formed with an independent charge generating layer and an independent charge transport layer laminated can provide a highly sensitive photosensitive member by the combination of a charge generating agent and a charge transport agent which are efficient in the use as the charge generating layer and the charge transport layer. Further, since materials can be selected in a broad range for each function, a photosensitive member having an optional characteristic (such as safety and coating property) can be produced comparatively easily at a low cost. For these many advantages, the laminated function-separated type photosensitive member is now the mainstream of the photosensitive member development.
However, laminated function-separated type photosensitive members practically used are inferior to conventional inorganic type photosensitive members in terms of the durability. In particular, the sensitivity is liable to deteriorate due to the deterioration of the electric characteristics such as decline of the charge potential and rise of the residual potential in the repeated use. This is due to deterioration or decomposition of the organic photoconductor compound or the binder resin occurs, or a structural carrier trap formation by the existence of an impurity in the photosensitive layer in the processes of charging, exposing, developing, transferring, and cleaning. Therefore, there are such limitations in terms of the printing durability in the practical use.
The storage stability of a coating liquid for a photosensitive member influences greatly not only the maintenance of the electric characteristics of the photosensitive member applied with the coating liquid but also the productivity or the cost of the photosensitive member. In order to ensure the storage stability, a method of using a charge generating agent or a charge transport agent, which is an organic electroconductive compound, and further, an additive for restraining the decomposition of a binder resin has been commonly adopted so far. For example, a method of adding an antioxidant in a photosensitive layer as disclosed in Japanese Unexamined Patent Publications 64-44451 (1989) and 7-146564 (1995) is well well known.
However, the conventional technology has a setback since the additive used (mainly antioxidant) deteriorates the electric characteristics when it remains in the photosensitive member, or deteriorates the film formation property and the surface property of the photosensitive layer. Accordingly, in order to ensure the stability of the coating liquid for a photosensitive member, it is preferable that such an additive can be eliminated easily in the manufacturing process of the photosensitive member.